What Nutrients Do I Need to Grow Cannabis?

by Nebula Haze

Do you need special fertilizer to grow weed? How do you choose good marijuana nutrients? Adding cannabis nutrients to your grow can help you get the best potency, yields and growth from your plants. Cannabis plants have two stages of life and they need the right nutrients at the right time.

What special nutrients do I need to grow cannabis?

Use a “Grow” (high N) nutrient formula for the first life stage of cannabis

Use a “Bloom” (low N) nutrient formula when buds are forming (in a pinch, "cactus food" can be used during budding until you get better nutrients - it has similar nutrient ratios)

Optimal Cannabis N-P-K Nutrient Ratios

Life Stage

N

P

K

Vegetative/Grow

High

Medium

Medium or High

Flowering/Bloom

Low

Medium or High

Medium or High

These aren't the only nutrient ratios that will work for growing cannabis, but these ones work well.

Note: Don’t use anything with time-released nutrients (like fertilizer spikes, or Miracle-Gro soil - they deliver too much N in the flowering stage).

There's so many cannabis nutrient options. This tutorial will help you figure out which cannabis nutrients are a great choice for your setup.

For All Cannabis Plants - Low Levels of Nutrients Given Regularly is Much Better Than Giving a Lot of Nutrients at Once!

Most nutrient bottles have 3 numbers, often called N-P-K, which stands for Nitrogen, Phosphorus and Potassium

(Why "K? The atomic symbol of Potassium is "K" from Neo-Latin kalium)

Cannabis plants need different ratios of these 3 nutrients (as well as several micronutrients) depending on what stage of life they are currently in.

For example, cannabis plants in the vegetative stage need nitrogen to power the growth of leaves. In the flowering/budding stage, cannabis needs less nitrogen and greater levels of phosphorus to assist with proper bud growth.

Because of the varied nutrient needs of the cannabis plant, it's often easier for many growers to use a professional nutrient system made for a plant like cannabis, instead of trying to mix up their own. With a professional nutrient system, you don't have to figure out your own changing nutrient ratios, and you don't have to worry about chemical reactions that occur from combining different types of nutrients incorrectly (which can create fertilizer salts and cause nutrient lock-out).

A professional cannabis nutrient system will save many growers a lot of time, frustration and money. There are many nutrient systems to choose from which have been created by long-time cannabis growers and breeders around the world!

When it comes to finding a nutrient system to use with your cannabis plants, the first questionyou ask yourself should be: "What is my growing medium?"

Warning: When it comes to growing cannabis, avoid any nutrients which claim to be "extended" or "slow release"! They can cause all types of unexpected problems.

If you are growing in any medium besides soil, like coco coir, or a soilless mix, you will want to get nutrients made for hydroponics. Some nutrients are even more specific, like Canna Coco is formulated to work best growing cannabis in Coco Coir.

With all nutrient systems, never start at full strength or it might burn your plants!

Different strains have different preferences, and some plants are very sensitive to nutrient burn.

I recommend with new nutrient systems to start at half-strength and only raise the amount as needed. Most growers will never need to raise nutrient levels above half-strength unless plants are under bright lights and are growing very fast.

Plants use light for food (and to power the growth of buds), not nutrients. Just like eating a bunch of multi-vitamins every day will make you sick, giving plants too high levels of nutrients can make them sick, too. With plants, just like humans, you will get the best results by paying attention to nutrient needs on a regular basis. Don't wait until your whole plant is yellowing to try to figure out the problem!

Some growers try to push their plants to the limit of what they can take, giving stronger and stronger levels of nutrients until plants show signs of nutrient burn, but I don't believe this is necessary. Sometimes less is more. I believe that as long as your plant is not showing signs of deficiencies (such as growing pale green leaves towards the bottom of the plant), you are generally in the right range.

Many cannabis growers will find that professional nutrients work well at half-strength, and only growers with very bright lights and fast-growing plants will need to raise nutrient levels above that. There are also certain strains that seem to do better at higher nutrient levels than most others.

Many of us have seen Miracle-Gro used around our homes, so we know that it works for ‘regular houseplants’. Cannabis is just a tough weed, so Miracle-Gro nutrients should work great for it, too... right?

No. Not really.

The biggest problem with Miracle-Gro nutrients is they use one formula for the entire plant life cycle. Most especially, it does not have the right ratio of nutrients for the flowering/budding phase of the cannabis plant's life.

Even if Miracle-Gro is good one for one stage of your plants growth, it won’t be good for all of them. The ratio of nutrients a cannabis plant needs changes drastically between when your plant is a seedling and when the plant is making buds in the flowering stage. Cannabis plants need a nutrient system to accommodate for their changing nutrient needs, and the standard Miracle-Gro formula just doesn't work well.

Please, save yourself the time and frustration - get a nutrient system that's proven to work for growng cannais! If cost is a worry...

Don't want to spend a lot? Need something simple?

Dyna-Gro Nutrients Work Great For Growing Cannabis

One of the simplest (yet still inexpensive) cannabis nutrient systems that works great for beginners is offered by Dyna-Gro. (Foliage-Pro, Bloom). Their system uses just two bottles and is very simple, plus they work with any growing medium for growing cannabis.

Dyna-Gro can be used to grow cannabis in...

soil

hydro

coco coir

...or any growing medium

Dyna-Gro nutients work well for growing cannabis from seed to harvest. You don't need anything else. They do not build up salt in your soil or growing medium like many other inexpensive fertilizers, and they will never clog your hydroponic system.

Dyna-Gro Nutrients famously worked better than Advanced Nutrients in a cannabis grow-off on Rollitup, which surprised many people since AN has long been considered one of the "golden standard" nutrient systems for growing cannabis (and it comes with a very expensive price tag, too).

Best of all, Dyna-Gro nutrients are cheap!

Vegetative
Stage

Use Dyna-Gro "Foliage-Pro" bottle during the Vegetative stage, while plants are growing stems and leaves. The Dyna-Gro "Grow" bottle can also be used. Like with any new nutrients for growing cannabis, start at half strength of what it says on the bottle, and only move up slowly - a little bit goes a long way!

Flowering
Stage

Use the Dyna-Gro "Bloom" bottle during the Flowering stage. Once your cannabis plant starts forming buds, you can continue to use just this one nutrient bottle until harvest. You can actually follow the instructions on the bottle (just start at half strength at first). It's super simple.

Not sure which soil should you start with? I recommend starting with Fox Farms Happy Frog soil and mixing the soil with about 30-40% perlite for a perfect cannabis soil starting mix. For the easiest soil growing, get a smart pot (a growing container made out of fabric - they work perfectly for growing cannabis).

Don't want to use nutrients? Learn how to mix up your own super soil so it has all the nutrients your cannabis plants will need! Bonus: With composted super soil made using the recipe in the link above, you don't need to worry about maintaining your pH! your super soil will automatically manage the pH for you.

The most common mistake made by beginners growing cannabis in soil is they water their plants too often. Overwatering is almost never a case of giving your plants too much water at once. Instead, overwatering cannabis in soil is almost always caused by giving the plant water too often.

How to water cannabis plants in soil

Wait until the top of your soil feels dry up to your first knuckle (about an inch deep)

Add nutrients to your water (if needed), then adjust the pH. Most soil growers only add nutrients every other watering, or even less often, but you will always need to adjust the pH of your water.

Start watering your plants and continue to add water until you see at least 20% extra runoff water drain out the bottom of your pot. Go back to step 1.

To get good results, always be careful to use your nutrients correctly. Follow the nutrient schedule provided by your nutrient line (I've included links to some nutrient schedules below). These dosing schedules will tell you exactly how much of each nutrient to add to your water, like a recipe.

For new nutrients you haven't grown with before, always start at half-strength and raise the amount slowly. Do not use nutrients with every watering! Most growers will add nutrients every other watering or even less frequently. Remember, a little bit goes a long way. You can always add more nutrient later, but it's a lot more difficult to take them back from the soil.

The Fox Farms trio works great for growing any cannabis strain, without needing any additional supplements.

There are three different bottles that you will need to grow cannabis, "Grow Big," "Big Bloom," and "Tiger Bloom." They are often sold together. Simply follow the included nutrient schedule (here's a PDF, here's a JPG) from Fox Farms.

Make sure you get the soil version if growing in soil, because Fox Farms offers a hydroponic version of the same nutrient line.

Fox Farms Nutrient Trio for Soil <-- Very concentrated, less is more. "Grow Big" & "Tiger Bloom" provide most of the major nutrients your cannabis needs, while "Big Bloom" has many micro nutrients and beneficial compounds that help nutrient uptake and root health. This trio works extremely well by itself, just follow the feeding schedule (here's a PDF, here's a JPG) from Fox Farms. They offer a lot of supplements, but the only bottles you need to be successful growing cannabis is the FF trio, which is highlighted in green on the schedule. The trio tends to be strong, so use it sparingly (especially "Grow Big" & "Tiger Bloom"). I recommend giving plain pH'ed water every other watering to make sure your plants only get exactly what they need.

Botanicare Pure Blend for Soil (Soil 2-pack for the Vegetative & Flowering Stage) <-- Recommended for Beginners becuase this nutrient system is easy to use, relatively cheap, and can be found at almost any hydro store or online. Botanicare Pure Blend for Soil works great for growing any cannabis strain, without needing a lot of extra care, or any additional supplements. The two bottles are all that's needed to get your plants successfully to harvest time. You can follow the instructions on the bottle or use the feeding schedule from Botanicare (here's a PDF, here's a JPG). They offer a lot of supplements, but the only bottles you need to be successful growing cannabis is the Pure Blend 2-pack, which is what's reflected in the "standard" version of their schedule. Repeat "Week 3" of the Vegetative part of their schedule until the end of the vegetative stage if it lasts longer than 3 weeks. For auto-flowering strains - skip week 3 of "Vegetative" & skip week 6-7 of "Flowering/Fruiting" - otherwise you can follow the instructions almost exactly.

Dyna-Gro (Foliage-Pro, Bloom) <-- Cheapest nutrients that still work great for growing cannabis in soil. Use "Foliage-Pro" during the vegetative stage, and "Bloom" during the flowering stage. Just follow the instructions on the bottles!

From a grower: “H&G was started by a top researcher from Canna. They are right outside of Amsterdam and because cannabis is legal there, so both Canna and H&G are able to do R&D using cannabis. I don't know about Canna, but I know that House and Garden makes all their own nutrients in house and they work great.”​

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This plant was grown using the House & Garden Line-up listed above

Don't want to use nutrients? Learn how to mix up your own super soil so it has all the nutrients your plants need! Bonus: With composted super soil, you don't need to worry about maintaining your pH! Instead, you are actually creating a specially made microbial soil mix that will automatically take care of the pH for your plants, while slowly feeding them the exact nutrients they need.

This complete nutrient system can be used in any cannabis growing medium, including hydroponics, coco coir, and even soil. The Flora series works amazingly well for growing cannabis, without needing a lot of fuss.

You don't need any other nutrients to grow marijuana; this trio alone will give your cannabis plants what they need to flourish through the vegetative and flowering stages.

I love growing with General Hydroponics Trio because I don't have to worry about nutrients and can focus on creating a great growing environment and harvesting my fat buds.

Simply follow the included nutrient schedule or the custom nutrient schedules listed above(start at half strength and increase as needed) and keep the pH of your water between 5.5-6.5 at the plant roots for best results. Or feel free to use my custom DWC schedule for the GH trio [PDF].

Unlike some nutrient systems, these nutrients are great for growing hydroponically with your plant roots directly in water. They don't contain loose particles and will not clog up your tubes, pumps or other hydroponic equipment.

General Hydroponics Flora Series Nutrient Trio <-- Recommended for Beginners. This is the system we use when growing hydroponically (can also be used in coco coir and soil). General Hydroponics is a trusted nutrient company and their Flora Trio works very well for beginners and advanced cannabis growers. They now offer a complete "performance pack" that includes everything needed to get started including a pH test kit. That way you don't have to buy a bunch of huge nutrient bottles at once. Feel free to check out a grow journal where we pulled in over 20 ounces from a single 600W tent using just this trio plus Aquashield for the roots (pic below). We didn't use anything else for the whole grow and were very happy with our results.

General Hydroponics FloraDuo (Bottle A & Bottle B) <-- From a grower: "This is a great choice by GH if 3 bottles seems like too much to deal with. You have less complete control, but it can be a better way to get a “sense” of what the plants need at each stage, since you’re only using two bottles." Another grower said: "Flora Duo are foundation tools in my eyes. If you're new and you really want success early on, a simple line like the Flora Duo is going to be good. Less bottles to play with, super simple feeding schedule, and you learn. People pick up on the fact that bottle A is high nitrogen, you use a lot of it the first half then it switches to bottle B that has more Phosphorus and Potassium. So you gain some understanding as to WHY you need both, and what different things do for the plant." Here's the FloraDuo Nutrient Schedule from General Hydroponics [PDF]

From a grower: “H&G was started by a top researcher from Canna. They are right outside of Amsterdam and because cannabis is legal there, so both Canna and H&G are able to do R&D using cannabis. I don't know about Canna, but I know that House and Garden makes all their own nutrients in house and they work great.”​

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Botanicare KIND Trio For Hydro (Base, Grow, Bloom) <-- The three bottles are all that's needed to get your plants successfully to harvest time, just follow the feeding schedule from Botanicare (here's a PDF, here's a JPG​) to start. They offer a lot of supplements, but the only bottles you need to be successful growing cannabis is the 3 listed (Base, Grow, Bloom), which is what's reflected in the "standard" version of their schedule. Repeat "Week 3" of the Vegetative part of their schedule until the end of the vegetative stage if it lasts longer than 3 weeks.

​

From a grower who wrote in: "I use the Botanicare KIND lineup - it seems to get good results, not too expensive, and works very well in hydro." Another grower told us, "As far as favorites go, I've been pretty pleased with Botanicare KIND, it's 'okay' when you follow the chart, but once you start tinkering with it, it'll really shine since it was developed to be played with." Apparently a lot of growers like tinkering with this trio as another grower said, "Botanicare KIND is like the opposite spectrum [of the Botanicare Pure Blend series]. The Base is just Nitrogen and Calcium. Grow and Bloom both have most of the minerals in them, along with things like seakelp! The Bloom is also 0-6-6. Grow at 2-2-4. So quite literally you can call the shots on Nitrogen and Calcium. That level of control hasn't been around a great deal in our market. For the savvy grower this is a pretty nice tool."

Aquashield(banish root rot for good and promote root health, in our tests Aquashield works better at getting rid of root rot than the 10x more expensive Great White supplement) Learn how we use Aquashield to get rid of and prevent root rot in a hydroponic environment.

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***Note: Advanced Nutrients (Grow, Micro, Bloom) offers an expensive nutrient line which is formulated for plants like cannabis, and many growers swear by it. It will definitely work for growing marijuana, no question about it. However, in side-by-side comparisons, cheaper nutrients systems often outperform Advanced Nutrients as far as cannabis yields, potency and flavor. I've never tried the Advanced Nutrients line due to the expensive price tag, especially since I've had such great results with so many other less expensive systems, but I felt the need to mention it because it's so often used to grow cannabis. Here's the Advanced Nutrients calculator to figure out how much you'll need to use: http://www.advancednutrients.com/hydroponics/calc/

Nutrient Picks For Growing in Coco Coir

Often when growing cannabis in coco coir, it is helpful to supplement with extra Calcium and Magnesium as calcium deficiencies & magnesium deficiencies are relatively common in coco coir. There are many supplements that provide a boost of these nutrients, and pretty much all of them will work fine. A commonly seen one called "Cal-Mag" by Botanicare works well (and is pretty inexpensive), and so does "CaliMagic" from General Hydroponics. Coco coir is an excellent growing medium as long as you maintain the pH between 5.5 - 6.5 and make sure the plants have enough calcium and magnesium.

Any quality cannabis nutrients made for hydroponics will work well for growing in coco coir as long as you also use a Cal-Mag supplement.

I personally like the General Hydroponics Flora trio plus Calimagic​ (a Cal-Mag supplement) for growing in coco coir. This is what I use for my coco coir grow. You can follow the nutrient schedule provided by GH as long as you provide plain water every other watering. Or...

Canna Coco A + B & Cal-Mag<-- This combo is a crowd favorite - many coco coir growers write in to tell us this is their favorite cannabis nutrient for growing in coco coir. From a grower: “Canna is a Dutch company and one of the best IMO. They make a great product line for growing in coco coir and test their products on real cannabis plants." Another grower said, "Canna products are one of the only nutrient lines to be developed primarily for cannabis (and tested on live plants). They've been doing so for almost 30 years. Cost is a little higher than competitors but worth every penny.” A different grower added, "Canna - I have only used their coco line, but it is the the highest quality you will find."

Fox Farms Nutrient Trio for Hydroponics & Cal-Mag<-- Very concentrated, less is more. This is what I used for my first few coco coir grows, and I was very happy with my results. "Grow Big" & "Tiger Bloom" provide most of the major nutrients your cannabis needs, while "Big Bloom" has many micro nutrients and beneficial compounds that help nutrient uptake and root health. This trio works extremely well by itself, just follow the feeding schedule (here's a PDF, here's a JPG) from Fox Farms. They offer a lot of supplements, but the only bottles you need to be successful growing cannabis is the FF trio, which is highlighted in green on the schedule. The trio tends to be strong, so use it sparingly (especially "Grow Big" & "Tiger Bloom"). Generally the Fox Farms nutrient system will prevent Cal-Mag deficiencies, but it's good to have extra Cal-Mag on hand just in case whenever growing cannabis in coco coir.​

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Dyna-Gro (Foliage-Pro, Bloom) & Cal-Mag<-- Cheapest nutrients that work well for growing cannabis in coco foir. Use "Foliage-Pro" during the vegetative stage, and "Bloom" during the flowering stage. Just follow the instructions on the bottles!

From a grower: “H&G was started by a top researcher from Canna. They are right outside of Amsterdam and because cannabis is legal there, so both Canna and H&G are able to do R&D using cannabis. I don't know about Canna, but I know that House and Garden makes all their own nutrients in house and they work great.”​

It's important to maintain the pH of your root environment to prevent nutrient problems.

The easiest way to do that is to test the pH of your water before you water your plants.

Some growers get lucky and successfully grow weed without testing the pH of their water, but most people who don't test for pH will start seeing signs of nutrient deficiencies and other nutrient problems.

This is because even if the right amounts of nutrients are present, your weed simply cannot absorb them if the pH isn't in the correct range.

It's actually really easy, quick, and cheap to learn how to check and adjust the pH of your water, and there are "pH test kits" specifically made for this purpose.

After you get the hang of it, checking and adjusting the pH and will take you less than 5 minutes each time you water your plants. And your results (monster yields with huge buds and healthy plants) speak for themselves.

Soil Optimal pH: 6.0 - 7.0Hydroponics Optimal pH: 5.5 - 6.5

Getting the pH exactly right isn't nearly as important as checking regularly and making sure it stays within these ranges.

When should I stop fertilizing during flowering? Not one website or blog has given a definitive answer. Is a nutrient "flush" necessary?

Lots of growers have different opinions about when to stop fertilizing during the flowering stage, and unfortunately there's no consensus. Many growers fertilize differently from each other and no one agrees one what's the right way. Some growers fertilize until the end, and some stop giving nutrients for days or weeks before harvest time.

If you're growing in soil, growers usually stop giving liquid nutrients sooner than in hydro. I've heard of soil growers flushing (giving just plain water) for up to a month or more before harvest time, or even longer. Other growers provide nutrients right until the end.

In hydro, most growers will flush from 0-14+ days.

I would make sure you provide flowering/bloom nutrients for at least the first few weeks of flowering, or longer. A common technique is to flush your plants for 2 weeks before harvest. So basically you wait until you think your plant is almost ready, and start flushing (giving just plain water with no extra nutrients).

When it comes to nutrients, I personally try to give as little nutrients as possible for the whole grow. As long as you aren't seeing deficiencies, you're giving enough nutrients and there's no need to go up. By providing relatively low levels of nutrients, you aren't building up extra nutrients in the plant which could affect taste. In this case, any sort of flush becomes less important.

With all nutrient systems that you're trying out for the first time, I highly suggest starting at half the recommended nutrient levels when growing weed.

Only increase the concentration of nutrients if you see signs of nutrient deficiencies.

This is because, for whatever reason, most nutrient recommendations are way too strong for growing most strains of cannabis. (Maybe nutrient companies want to sell more by having you use more?)

So if the included nutrient schedule say add a teaspoon to a gallon of water, I'd say you cut that in half and add a ½ teaspoon to a gallon of water. If it says to add 2ml to a liter of water, than you add 1ml to a liter of water.

With nutrients, a little bit goes a long way.

I've found over and over that you get the best yields by erring on the side of "too little" over "too much" nutrients. I always start a half strength and only move up when I see deficiencies.

For example, I do increase nutrient levels if I notice slight yellowing of leaves towards the bottom of the plant.

Increase Nutrient Levels If You See This

(click picture for more information)

Now yellowing leaves towards the bottom of your plant is okay if you're late in the flowering stage, but this symptom needs to be corrected at any other time earlier in the plant's life (to make sure you have enough leaves that last all the way to the end).

How much is too much nutrients?

I recommend providing just enough nurients to avoid signs of underfeeding. I tend to start nutrients at half-strength and only raise the strength if I noticed signs of nutrient deficiencies (usually starting with pale or yellowing lower leaves).

Some growers try to “push the limits” to feed as much nutrients as possible without causing nutrient burn. I recommend against this method because nutrient burn is permanent - if you burn your plants, all those leaves will be permanently burned. If buds have already started forming, you can cause nutrient burn on your actual sugar leaves on your buds, causing the appearance of your harvested buds to appear rough, even if the buds themselves are fine.

For hydro growers, checking the PPM of your water is one of the best ways to see whether your plants need more or less nutrients. Learn more about PPM in hydro here. For a hand-waterd plant, one of the best thing to do is check the PPM of both your nutrient water going in and the run-off water coming out the bottom. So for example if you add nutrient-water at 1000 PPM and watch the run off you'll be able to track the change; if the PPM goes up it’s clear there is enough nutrient already, perhaps even too much. If the PPM drops, you know you can continue with feeding because your plant is taking in enough nutes to prevent any from being left over as extra.

Why do I need a special type of fertilizer to grow cannabis, aren't they just weeds in the wild? Why can't they grow in regular dirt?

While cannabis plants will grow in a lot of conditions, as a farmer, you are looking to optimize the size, weight, density, potency and overall quality of your buds. In order to do that, you will need to fertilize your cannabis plants in such a way that they can produce at their best.

Yes, you can plant weed seeds in dirt and possibly grow a plant without any fertilizers or special nutrients. But chances are that you don't happen to live in a place with very rich, fertilized soil that carries just the right blend of nutrients needed by a marijuana plant to thrive.

Cannabis plants which don't get the right levels they need, especially in the flowering/budding phase, tend to grow small and airy buds. In extremely poor conditions, some cannabis plants may just sprout a few white hairs (pistils), and never actually form any real buds at all.

Because of that, I encourage growers to learn about the type of nutrients and special fertilizers needed by a cannabis plant, and at least start with good soil before you get started growing if you're determined not to use any nutrients.

If you want to grow the biggest buds you can, but you're just don't have the money to buy fancy nutrients, I encourage you to learn about Dyna-Gro, a very cheap nutrient option that's proven to work great for growing cannabis in just about any growing medium, whether you're growing in soil or hydro.

And if you are determined to grow organically, I encourage you to learn about how you can actually compost your own organic super soil in such a way that you actually don't ever need to add any extra nutrients at all.

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